Insert molding

ABSTRACT

A method and apparatus involve positioning an insert within a cavity of a mold, heating an insert wall within the cavity of the mold, and casting a molten metal into the cavity adjacent the insert. A surface of the insert absorbs heat from the molten metal to melt and fuse to the molten metal.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

The present application claims priority under 35 USC 119(e) fromco-pending U.S. Provisional Patent Application Ser. No. 61/091,726 filedon Aug. 25, 2009 by Mark A. Baumgarten and entitled “INSERT MOLDING”,the full disclosure of which is hereby incorporated by reference.

BACKGROUND

Insert molding is a term used in the metal casting industry to describethe inclusion of a loose insert or inserts within the mold cavity whichafter the molten cast material has been introduced into the mold cavityand the cast geometry has solidified the insert or inserts and castmaterial have become one unit. Attaining a sufficiently strong bondbetween an insert or inserts and the cast geometry is difficult.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an insert molding system accordingto an example embodiment.

FIG. 2 is a schematic illustration of another embodiment of the insertmolding system of FIG. 1 according to an example embodiment.

FIG. 3 is a schematic illustration of the insert molding system of FIG.2 during insert molding.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

FIG. 1 is a schematic illustration of an insert molding system 20according to an example embodiment. As will be described in more detailhereafter, insert molding system 20 provides a stronger and morereliable bond between an insert and the cast geometry about the insert.The enhanced junction between the insert and the cast geometry about theinsert further enhances thermal conductivity between the insert and thecast geometry about the insert. In one embodiment, insert molding system20 joins an insert and cast geometry of like or similar metals ofnon-ferrous metals using electrical current within a controlledatmosphere to create a metallurgical bond at the interface of the insertand the cast geometry eliminating the need for secondary joiningprocesses. The metered combination of parameters used in creating theatmosphere within the closed cavity and the heat created by theintroduction of electrical current to the metal insert “excite” themetallurgical structure of the insert, which at a surface level, fusetogether with the molten cast material to form a bond. The introductionof a shielding gas (an inert gas such as argon) to the mold cavity asthe alloy insert is being heated can minimize the formation of oxidesthat can have a negative impact on a preferred bond quality.

Insert molding system 20 generally includes mold 22, insert supports 24,insert heating system 26, gas introduction system 28, casting system 30,release agent system 31 and controller 32. Mold 22 comprises two or morestructures forming a cavity 36 configured to receive an insert 38(statically shown). Mold 22 is configured to be separated into itsconstituent parts to allow insertion of insert 38 and removal of insert38 along with the cast material about insert 38. In one embodiment, mold22 is formed from one or more metals or metal alloys, such as steel.Although illustrated as being generally rectangular, cavity 36 may haveany of a variety of shapes or configurations depending upon the desiredfinal shape or configuration of the product resulting from the insertmolding.

Although insert 38 is illustrated as being generally rectangular inshape, insert 38 may also have any of a variety of different shapes,sizes and configurations. For example, in one embodiment, insert 38 maycomprise a cylinder. Insert 38 is generally formed from one or morematerials, wherein a surface of insert 38 is provided by a metal. Forpurposes of this disclosure, the term “metal” by itself includesindividual metal elements as well as alloys of two or more metalelements. In one embodiment, insert 38 has surface portions formed froma first alloy (a combination of two or more metal elements), wherein thecast molten metal is an alloy from the same family (i.e. the samecombination of two or more metal elements, albeit potentially havingdifferent percentages of the two or more metal elements).

In one embodiment, insert 38 may be additionally be pre-wetted orpre-fluxed along its surface to facilitate bonding with cast moltenmetals, such as metals not of the same alloy family. For example, in oneembodiment, insert 38 may have copper surface portions which arepre-wetted or pre-fluxed to facilitate soldering or brazing of castmolten lead, zinc, copper or brass metals about insert 38.

In one embodiment, insert 38 may comprise a cylinder formed fromaluminum. In other embodiments, insert 38 may have other configurations,including more complex shapes, and may be comprised of severalcomponents of other materials as an assembly including alloys of like oralloy as well as other metals or non-metallic materials. For example,insert 38 may have interior non-metal portions connected to or insulatedfrom an exterior metal surface. Although system 20 is illustrated asusing one insert 38, in other embodiments, system 20 may cast aboutmultiple inserts within cavity 36.

Insert supports 24 comprise structures within mold cavity 36 and withinmold 22 configured to support and retain insert 38 in place during theintroduction of molten cast alloy into cavity 36. In one embodiment,such insert supports 24 may be joined, fastened, well become bonded orintegrally formed as part of a singer unitary body with mold 22. In oneembodiment, a portion of inserts 24 may extend into or through insert38. In one particular embodiment, insert supports 24 may be omitted.

Insert heating system 26 comprises a system configured to heat insert 38while insert 38 is within cavity 36 prior to casting the molten alloyabout insert 38. Insert heating system 26 is configured to heat insert38 such that the temperature of insert 38 is below the meltingtemperature of the alloy to make contact with the molten cast alloy.Although the temperature to which insert surface portion 40 is heated isbelow the melting temperature of the material of surface portion 40, theattained temperature is such that when surface portion 40 absorbsadditional heat from multitasking 36 (when cavity 36 or mold 22 areheated) the molten cast metal introduced by casting system 30, thetemperature of surface portion 40 rises to a temperature above themelting point of surface portion 40. As a result, surface portion 40melts and fuses with the molten cast metal introduced by casting system30 about insert 40. As a result, at least surface portion 40 of insert38 becomes autogenous with the cast metal from casting system 30. Thiscreates a stronger bond as well as enhanced thermal conductivity betweeninsert 38 and the cast outer material. In one embodiment, one ormultiple distinct surface portions of insert 38 may be heated by insertheating system 26. In yet another embodiment, substantially an entireouter surface of insert 38 may be heated to the initial temperature suchthat the entire outer surface of insert 38 melts and fuses with themolten cast alloy introduced by casting system 30.

As shown by FIG. 1, insert heating system 26 heats insert 38 whileinsert 38 is within cavity 36. As a result, insert 30 is heated withinthe closed volume provided by cavity 36 of mold 22. This closed volumecreates a controllable environment that may tend to reduce the amount ofoxygen coming into contact with the surface of insert 38 during heating.By reducing the amount of oxygen coming into contact with the surface ofinsert 38 during heating, oxidization of the surface of insert 38 isreduced to further enhance the quality of the bonding, “soldering” or“welding” of the surface of insert 38 to the cast alloy from castingsystem 30. In other words, any reduction of oxides formed on the surfaceof insert 38 will enhance the quality of the bond between the cast metaland insert 38.

According to one embodiment, insert heating system 26 includes anelectrical heating system configured to apply an electrical currentthrough and across insert 38. The metal of insert 38 has an electricalresistance such that insert 38 is heated by the electrical current. Inone embodiment, insert heating system 26 includes an electric currentsource and a positive terminal and a negative terminal configured tocontact insert 38 when insert 38 is received within cavity 36. Becauseelectrical current is used to heat insert 38, insert 38 may be quicklyand rapidly heated to a controlled temperature slightly below themelting temperature of the metal insert 38. As noted above, thistemperature may be controlled such that additional heat absorbed by themolten cast metal from casting system 30 causes the like metal insert 38to cross the melting threshold and fuse with the like molten cast metalof casting system 30. The rapid heating of insert 38 to requiredtemperature and the timely introduction of molten cast metal fromcasting system 30 reduces the time that heated insert 38 is exposed tooxygen or other non-inert gases. This reduced exposure time reducespotential oxidation of the surface of the metal insert 38, furtherenhancing the quality of the bond between the metal insert 38 to thelike cast metal.

In such an embodiment wherein insert heating system 26 comprises anelectrical heating system configured to transmit an electrical currentthrough and across insert 38, insert supports 24 are formed from anelectrically insulating or electrically non-conductive material ormaterials. Such insulating insert supports 24 inhibit the electricalcurrent from being conducted to mold 22 by insulating between insert 40and mold 22. In one embodiment, the insulating supports 24 are formedfrom one or more non-conductive materials. In one embodiment, theinsulating supports 24 comprise rings or discs between insert 38 andmold 22. In other embodiments, such electrical insulating insertsupports 24 may have other shapes depending upon the shape of the one ormore inserts 38 and the geometric configuration of the mold 22.

As noted above, because insert 38 is heated within a contained,controlled volume or cavity 36 of mold 22, insert 38 is less susceptibleto oxidation or reaction with other non-inert gases. Gas introductionsystem 28 provides further shielding of insert 38 from oxidation duringheating of insert 38. Gas introduction system 28 comprises a device tosystem configured to introduce a shielding gas or inert gas, such asargon, into cavity 36 during the heating of insert 38 by insert heatingsystem 26. In one embodiment, system 20 is further configured to expelany oxygen from cavity 36 prior to the introduction of the shielding gasor inert gas and heating of the insert 38. For example, in oneembodiment, system 20 may include a vacuum system 39 which not onlydraws oxgyen, air or other non-inert gases from cavity 36, but alsodraws the shielding gas or inert gas into cavity 36. After the air isdrawn from cavity 36 to create a vacuum in cavity 36, a source or volumeof inert gas is connected to cavity 36 such that the inert gas issucked, drawn or pulled into cavity 36. The gas provided by gasintroduction system 28 shields surfaces of insert 38 from interactingwith oxygen during the heating of insert 38. In other embodiment, gasintroduction system 28 may be omitted.

Casting system 30 comprises a system configured to introduce moltenfluid material, such as a metal elements or alloys thereof, into cavity36 adjacent to surface portion 40 of insert 38 or about insert 38. Inone embodiment, casting system 30 comprises a die casting system. Inanother embodiment, casting system 30 may comprise a gravity castingsystem. As noted above, casting system 30 supplies the molten metal tocavity 36 at a sufficiently high temperature such that the heat added bythe molten material heats at least surface portion 40 of insert 38 to atemperature above the melting temperature and melting threshold of thematerial of surface portion 40. As a result, insert 38 becomesautogenous with the molten metal upon cooling and solidification of themolten metal about insert 38.

Given the limitations of commonly used cavity coatings used to preventcast metals from soldering or sticking to cavity surfaces, a releaseagent may be required as a supplement. Release agent system 31 comprisesa system to apply a layer 44 of release agent along the interior ofcavity 36. This layer of release agent facilitates separation of thecast part (and insert 40) from mold 22 upon separation or opening ofmold 22.

In the example illustrated, release agent system 31 includes releaseagent charger 48 and release coating supply 50. Release agent charger 48comprises a device configured to electrostatically charge release agent50 so that it will be drawn to the grounded surfaces of mold 22. In oneembodiment, release coating 50 comprises a powdered die lubricant (orrelease agent) configured to be attracted to grounded surfaces (similarto powder coating applications). As a result, the release agent 50supplied by release agent system 31 adheres to those grounded surfacesof mold 22. Since insert supports 24 are electrically insulated ornon-conductive, the release coating does not adhere to such supports 24.

In those embodiments in which insert heating system 26 is an electricalheating system that applies electrical current through and across insert38 to heat insert 38, release agent system 31 coats the groundedsurfaces of cavity 36 (other than insert 38) with electrostaticallycharged release agent 50. Release agent 50 is a particulate which whenelectrostatically charged adheres to the grounded cavity surfaces towhich it is applied (as performed in the painting process know aspowder-coating). Release agent system 31 is cycled while the mold isopen and prior to the placing of the insert or inserts in cavity 36(schematically shown). As insert supports 24 are made of non-conductivematerials, the electrostatically charged particles of release agent 50will not bond to insert supports 24. An air blow-off system 53 may beused to clear any excess release agent material from the mold surfacesprior to placing the insert or inserts in cavity 36. Preventing aconductive “bridge” between mold 22 and insert 38 minimizes downtime inproduction due to electrical faults. For example, many die releaseagents are water-born or in solution with other electrically conductivefluid materials. If the later agents are applied along the interior ofmold 22 during the operation of insert molding system 20, electriccurrent may be conducted from insert 38 to mold 22 faulting the system.In other embodiments, release agent system 31 may apply a releasecoating in other fashions without release agent charger 48. In otherembodiments, release agent system 31 may be configured to introduce theelectrostatically charged release agent 50 to the grounded surfaces ofmold 22 while the mold is closed such as with the use of the LEOMACSSYSTEM commercially available from the TOSHIBA MACHINE CO., LTD, whereinan electrostatically charged dry die lubricant (or release agent) isdrawn into the closed mold, by vacuum, from a port in the shot sleeve.In the later embodiment, the mold would have to be opened again to haveany loose particulate about insert supports 24 cleared away by airblow-off system 53 prior to placing the insert or inserts in cavity 36.This additional opening and closing of the mold would increase cycletime but applying the dry die lubricant (or release agent) while themold is closed is an environmentally cleaner process.

Controller 32 comprises one or more processing units configured tocontrol the operation and timing of mold 22, insert heating system 26,gas introduction system 28, casting system 30 and release agent system31. For purposes of this application, the term “processing unit” shallmean a presently developed or future developed processing unit thatexecutes sequences of instructions contained in a memory. Execution ofthe sequences of instructions causes the processing unit to performsteps such as generating control signals. The instructions may be loadedin a random access memory (RAM) for execution by the processing unitfrom a read only memory (ROM), a mass storage device, or some otherpersistent storage. In other embodiments, hard wired circuitry may beused in place of or in combination with software instructions toimplement the functions described. For example, controller 32 may beembodied as part of one or more application-specific integrated circuits(ASICs). Unless otherwise specifically noted, the controller is notlimited to any specific combination of hardware circuitry and software,nor to any particular source for the instructions executed by theprocessing unit.

In the example illustrated, controller 32 generates control signalsdirecting release agent charger 48 to electrostatically charge releaseagent 50. Controller 32 further generates control signals directing asupply of charged release agent 50 to be applied apply to the groundedinterior surfaces of mold 22 forming release layer 44. In embodimentswhere system 20 omits release agent system 31, such steps by controller32 may be omitted.

Upon application of release layer 44, controller 32 further generatescontrol signals to close mold 22 after insertion of insert 38 betweensupports 24. Such insertion of insert 38 (or multiple inserts 38) may beautomated (utilizing robotics) or performed manually. Controller 32further generates control signals directing gas introduction system 28to expel air from cavity 36 and to introduce an inert gas into cavity36. Once the metered charge of inert gas has been provided about insert38, controller 32 generates control signals directing insert heatingsystem 26 to rapidly heat insert 38 to a temperature slightly below themelting temperature of the one or more materials along the exteriorsurface of insert 38. In one embodiment, controller 32 directs insertheating system 26 to apply an electrical current through and acrossinsert 38. During such heating the inert gas atmosphere about insert 38inhibits the formation of oxides on the surface of insert 38.

Once insert 38 or surfaces of insert 38 have been heated to atemperature just below the melting threshold of the metal insert 38,controller 32 generates control signals directing casting system 30 tointroduce the molten cast metal into cavity 36, adjacent to surfaceportion 40 and about insert 38. Prior to contact of the molten castmetal with insert 38, controller 32 generates control signalsterminating the application of electrical current to insert 38. In oneembodiment, controller 32 may generate control signals terminating theapplication of current to insert 38 prior to the initiation of moltencast metal into cavity 36. In another embodiment, controller 32 may takeinto account the time required for the molten cast metal to contactinsert 38 and may be configured to terminate the application ofelectrical current to insert 38 by system 26 immediately prior to suchcontact if deemed necessary to maximize bond quality, optimize cycletime, or other. In those embodiments in which insert heating system 26does not employ electrical current to heat insert 38, such steps bycontroller 32 may be omitted.

FIGS. 2 and 3 illustrate insert molding system 120, a particularembodiment of system 20. Like system 20, system 120 provides a strongerand more reliable bond between an insert and the cast geometry about theinsert. The enhanced junction between the insert and the cast geometryabout the insert further enhances thermal conductivity between theinsert and the cast geometry about the insert. In one embodiment, insertmolding system 20 joins an insert and cast geometry of like or similarmetals of non-ferrous metals using electrical current within acontrolled atmosphere to create a metallurgical bond at the interface ofthe insert and the cast geometry eliminating the need for secondaryjoining processes. The metered combination of parameters used increating the atmosphere within the closed cavity and the heat created bythe introduction of electrical current to the alloy insert “excite” themetallurgical structure of the insert, which at a surface level, fusetogether with the molten cast material to form a bond. The introductionof a shielding gas (an inert gas such as argon) to the mold cavity asthe metal insert is being heated can minimize the formation of oxidesthat can have a negative impact on a preferred bond quality.

In the example illustrated, system 120 generally includes mold 122,insert supports 124, insert heating system 126, gas introduction system128, casting system 130, release agent system 31 (shown in FIG. 1),ejection system 131 and controller 32 (shown in FIG. 1). Mold 122comprises two or more structures forming a substantially closed orcontained cavity 136 configured to receive an insert 138 (schematicallyshown). Mold 122 is configured to be separated into its constituentparts to allow insertion of insert 138 and removal of insert 138 alongwith the cast metal about insert 138. As shown by FIG. 2, mold 122includes a vent 123. Vent 123 allows air or other non-inert gases to bepushed or discharged from cavity 136. At the same time, vent 123 issufficiently small or appropriately spaced from a location at whichmolten metal is introduced by casting system 130 such that the moltenmetal does not flow through vent 123 during casting of the molten metal.In one embodiment, vent 123 may alternatively be connected to a vacuumsystem, such as vacuum system 39 (shown and described above with respectto system 20). Although mold 122 additionally includes other variousopenings, such openings are closed off by other components such as withelectrodes, ejection pins or the like. In one embodiment, mold 122 isformed from one or more metals or metal alloys, such as steel. Althoughillustrated as being generally rectangular, cavity 136 may have any of avariety of shapes or configurations depending upon the desired finalshape or configuration of the product resulting from the insert molding.

Although insert 138 is illustrated as a cylinder, in other embodiments,insert 138 may have any of a variety of different shapes, sizes andconfigurations. Insert 138 is generally formed from one or morematerials, wherein a surface of insert 138 is provided by one or moremetals. In one embodiment, insert 138 has surface portions formed from afirst alloy (a combination of two or more metal elements), wherein thecast molten metal is an alloy from the same family (i.e. the samecombination of two or more metal elements, albeit potentially havingdifferent percentages of the two or more metal elements). In oneembodiment, insert 138 may comprise a cylinder formed from aluminum. Inother embodiments, insert 138 may have other configurations, includingmore complex shapes, and may be comprised of several components of othermaterials as an assembly including alloys of like or alloy as well asother metals or non-metallic materials. For example, insert 138 may haveinterior non-metal portions connected to or insulated from an exteriormetal surface. Although system 120 is illustrated as using one insert38, in other embodiments, system 120 may cast about multiple insertswithin cavity 136.

Insert supports 124 comprise structures within mold cavity 136 andwithin mold 122 configured to support and retain insert 138 in placeduring the introduction of molten cast alloy into cavity 36. In oneembodiment, such insert supports 124 may be joined, fastened, wellbecome bonded or integrally formed as part of a singer unitary body withmold 122. In one embodiment, a portion of inserts 24 may extend into orthrough insert 138. In the particular example illustrated, insertsupports 124 extend on opposite axial ends of insert 138 and furtherextend through insert 138. In some embodiments, insert supports 124 maybe omitted.

Insert heating system 126 comprises a system configured to heat insert138 while insert 138 is within cavity 136 prior to casting the moltenmetal about insert 138. Insert heating system 126 is configured to heatinsert 138 such that the temperature of insert 138 is below the meltingtemperature of the alloy to make contact with the molten cast alloy.Although the temperature to which insert surface portion 140 is heatedis below the melting temperature of the material of surface portion 140,the attained temperature is such that when surface portion 140 absorbsadditional heat from cavity 136 (when cavity 136 or mold 122 are heated)the molten cast metal introduced by casting system 130, the temperatureof the surface portion 140 of insert 138 rises to a temperature abovethe melting point of surface portion 140. As a result, surface portion140 melts and fuses with the molten cast metal introduced by castingsystem 130 about insert 138. As a result, at least surface portion 140of insert 138 becomes autogenous with the cast metal from casting system130. This creates a stronger bond as well as enhanced thermalconductivity between insert 38 and the cast outer material. In oneembodiment, one or multiple distinct surface portions of insert 138 maybe heated by insert heating system 126. In yet another embodiment,substantially an entire outer surface of insert 138 may be heated to theinitial temperature such that the entire outer surface of insert 138melts and fuses with the molten cast alloy introduced by casting system130.

As shown by FIG. 1, insert heating system 126 heats insert 38 whileinsert 138 is within cavity 136. As a result, insert 130 is heatedwithin the closed volume provided by cavity 136 of mold 122. This closedvolume creates a controllable environment that may tend to reduce theamount of oxygen coming into contact with the surface of insert 138during heating. By reducing the amount of oxygen coming into contactwith the surface of insert 138 during heating, oxidization of thesurface of insert 138 is reduced to further enhance the quality of thebonding, “soldering” or “welding” of the surface of insert 138 to thecast alloy from casting system 130. In other words, any reduction ofoxides formed on the surface of insert 138 will enhance the quality ofthe bond between the cast metal and insert 138.

In the example illustrated, insert heating system 126 includes anelectrical heating system configured to apply an electrical currentthrough and across insert 138. Insert heating system 126 includes anegative electrode 141 and a positive electrode 143. Electrodes 141 and143 apply an electrical current through and across insert 138. The metalof insert 138 has an electrical resistance such that insert 138 isheated by the electrical current. Because electrical current is used toheat insert 138, insert 138 may be quickly and rapidly heated to acontrolled temperature slightly below the melting temperature of themetal insert 138. As noted above, this temperature may be controlledsuch that additional heat absorbed by the molten cast metal from castingsystem 130 causes the surface of metal insert 138 to cross the meltingthreshold and fuse with the like molten cast metal of casting system130. The rapid heating of insert 138 to the required temperature and thetimely introduction of molten cast metal from casting system 130 reducesthe time that heated insert 138 is exposed to oxygen or other non-inertgases. This reduced exposure time reduces potential oxidation of thesurface of the metal insert 138, further enhancing the quality of thebond between the metal insert 138 to the like cast metal.

In such an embodiment wherein insert heating system 126 comprises anelectrical heating system configured to transmit an electrical currentthrough and across insert 138, insert supports 24 are formed from anelectrically insulating or electrically non-conductive material ormaterials. Such insulating insert supports 124 inhibit the electricalcurrent from being conducted to mold 122 by insulating between insert138 and mold 122. In one embodiment, the insulating supports 124 areformed from one or more non-conductive materials. In one embodiment, theinsulating supports 124 comprise rings or discs between insert 138 andmold 122. In other embodiments, such electrical insulating insertsupports 124 may have other shapes depending upon the shape of the oneor more inserts 38 and the geometric configuration of the mold 122.

As noted above, because insert 138 is heated within a contained,controlled volume or cavity 136 of mold 122, insert 38 is lesssusceptible to oxidation or reaction with other non-inert gases. Gasintroduction system 128 provides further shielding of insert 138 fromoxidation during heating of insert 138. Gas introduction system 128comprises a device or system configured to introduce a shielding gas orinert gas, such as argon, into cavity 136 prior to or during the heatingof insert 138 by insert heating system 126. In one embodiment, system120 is further configured to expel any oxygen from cavity 36 prior tothe introduction of the shielding gas or inert gas and heating of theinsert 138.

In the example illustrated, gas introduction system 128 includes aninert gas injection port 145 through which inert gas may be introducedinto chamber 136. In the example illustrated, gas introduction system or128 further includes an additional or alternative inert gas injectionport 147 through which inert gas may be induced into cavity 136. As willbe described hereafter, the regulation of flow of inert gas through port147 is partially controlled by the ejection system 131. In otherembodiments, one of ports 145 and 147 may be omitted. In yet otherembodiments, inert gas may be introduced by gas introduction system 128in other fashions.

Casting system 130 comprises a system configured to introduce moltenfluid material, such as a metal elements or alloys thereof, into cavity136 adjacent to surface portion 140 of insert 138 or about insert 138.In one embodiment, casting system 130 comprises a die casting system. Asshown by FIG. 2, casting system 130 includes a shot sleeve 151, a shotrod 153 connected to a plunger tip 154. Shot sleeve 151 comprises a tubeor sleeve having a pour hole 155 through which molten metal 158 may besupplied to into sleeve 151. Shot rod 153 and its plunger tip 154 areconnected to a powered actuator (not shown) which drives the moltenmetal 158 within sleeve 151 through a gating and runner system 160 intocavity 136 about insert 138.

In another embodiment, casting system 30 may comprise a gravity castingsystem. As noted above, casting system 130 supplies the molten metal tocavity 136 at a sufficiently high temperature such that the heat addedby the molten material heats at least surface portion 140 of insert 138to a temperature above the melting temperature and melting threshold ofthe material of surface portion 140. As a result, insert 138 becomesautogenous with the molten metal upon cooling and solidification of themolten metal about insert 138.

Given the limitations of commonly used cavity coatings used to preventcast metals from soldering or sticking to cavity surfaces, a releaseagent may be required as a supplement. Release agent system 31 (shown inFIG. 1) comprises a system to apply a layer 44 of release agent alongthe interior of cavity 136. This layer of release agent facilitatesseparation of the cast part (and insert 40) from mold 122 uponseparation or opening of mold 122.

In the example illustrated, release agent system 31 (schematically shownin FIG. 1) includes release agent charger 48 and release coating supply50. Release agent charger 48 comprises a device configured toelectrostatically charge release agent 50 so that it will be drawn tothe grounded surfaces of cavity 136. In one embodiment, release coating50 comprises a powdered dry die lubricant (or release agent) configuredto be attracted to grounded surfaces (similar to powder coatingapplications). As a result, the release agent 50 supplied by releaseagent system 31 adheres to those grounded surfaces of mold 122. Sinceinsert supports 124 are electrically insulated or non-conductive, therelease coating does not adhere to such supports 124.

In those embodiments in which insert heating system 126 is an electricalheating system that applies electrical current through and across insert138 to heat insert 138, release agent system 31 coats grounded surfacesof cavity 136 (other than insert 38) with electrostatically chargedrelease agent 50. Release agent 50 is a particulate which whenelectrostatically charged adheres to the grounded surfaces of the cavityto which it is applied (as performed in the painting process know aspowder-coating). Release agent system 31 is cycled while the mold isopen and prior to the placing of the insert or inserts in cavity 36(schematically shown). As insert supports 124 are made of non-conductivematerials, the charged particles of release agent 50 will not bond toinsert supports 124. An air blow-off system 53 may be used to clear anyexcess release agent material from the mold surfaces prior to placingthe insert or inserts in cavity 136. Preventing a conductive “bridge”between mold 122 and insert 138 minimizes downtime in production due toelectrical faults. For example, many die release agents are water-bornor in solution with other electrically conductive fluid materials. Ifthe later agents are applied along the interior of mold 122 during theoperation of insert molding system 20, electric current may be conductedfrom insert 138 to mold 122 faulting the system. In other embodiments,release agent system 31 may be configured to introduce theelectrostatically charged release agent 50 to the grounded surfaces ofcavity 136 while the mold is closed such as with the use of “The NewLEOMACS System” wherein an electrostatically charged dry die lubricant(or release agent) is drawn into the closed mold, by vacuum, from a portin the shot sleeve. In the later embodiment, the mold would have to beopened again to have any loose particulate about insert supports 124cleared away by air blow-off system 53 prior to placing the insert orinserts in cavity 136. This additional opening and closing of the moldwould increase cycle time but applying the dry die lubricant (or releaseagent) while the mold is closed is an environmentally cleaner process.

Ejection system 131 comprises a device or mechanism configured to ejectthe completed product from cavity 136 when mold 122 is opened. In theexample illustrated, ejection system 131 includes an ejection pin 163connected to an actuator (not shown). As the actuator advances ejectorpin 163, and possible others, the cast geometry and the insert 138bonded thereto, are ejected from cavity 136. In one embodiment, ejectionpin 163 also serves as a valve for opening and closing inert gasinjection port 147.

Controller 32 (schematically shown in FIG. 1) comprises one or moreprocessing units configured to control the operation and timing of mold122, insert heating system 126, gas introduction system 128, castingsystem 130, release agent system 31 and ejection system 131. In theexample illustrated, controller 32 generates control signals directing asupply of electrostatically charged release agent 50 to be applied applyto the grounded interior surfaces of mold 122 forming release layer 144(shown in FIG. 1). In embodiments where system 120 omits release agentsystem 31, such steps by controller 32 may be omitted.

FIGS. 2 and 3 illustrate the insert molding process. As shown by FIG. 2,upon application of release layer 144, controller 32 further generatescontrol signals to close mold 122 after insertion of insert 138 betweensupports 124. Such insertion of insert 138 (or multiple inserts 138) maybe automated (utilizing robotics) or performed manually. Controller 32further generates control signals directing are causing the introductionof molten metal 158 through pour hole 155 into shot sleeve 151.

During or prior to the introduction of the molten metal 158 into shotsleeve 151, controller 32 also generates control signals directing gasintroduction system 128 to supply inert gas through port 145 into sleeve151. As inert gas is pushed into cavity 36, existing air within cavity136 is pushed out of cavity 136 through vent 123. During the time periodthat the inert gas has surrounded insert 138, controller 32 generatescontrol signals causing insert heating system 126 to heat insert 138. Asnoted above, in the example illustrated, this is achieved by supplyingan electrical current through and across insert 138 using electrodes 141and 143. During such heating, molten metal 158 has not yet reachedinsert 138. Prior to the molten metal 158 reaching insert 138,controller 32 generates control signals terminating the heating ofinsert 138 are cutting off the supply of electrical current to insert138.

As further shown by FIG. 2, in some of embodiments, inert gas may alsobe introduced through port 147. During such introduction, ejection pin163 is withdrawn from port 147, opening port 147. Gas introductionsystem 128 pushes inert gas through port 147 into cavity 136. Theintroduction of inert gas through port 147 may be used independently orin combination with the introduction of inert gas through port 145.

As shown by FIG. 3, after insert 138 has been sufficiently heated in thepresence of the inert gas, controller 32 generates control signalsdirecting an actuator (not shown) to drive shot rod 153 and its plungertip 154 to push molten metal 158 through gating and runner system 160into cavity 136 about insert 138. Movement of plunger tip 154 blocks orinterrupts the flow of additional inert gas through port 145 into cavity136. At this time controller 32 also generates control signals to closethe valve allowing the introduction of inert gas through port 147.During such injection or casting of molten metal 158 into cavity 136,controller 32 also generates control signals directing an actuator (notshown) to move the ejection pin 163 to the position shown in FIG. 3 inwhich ejection pin 163 closes off port 147, interrupting the flow ofinert gas through port 147. In particular, during the injection ofmolten metal 158 into cavity 136, the tip of the ejector pin 163 isadjacent to cavity 136. The heat introduced by the molten metal 158 ispartially absorbed by the exterior portions of insert 138 to raise thetemperature of such surface portions of insert 138 above the meltingthreshold of such surface portions. As a result, the surface portions ofinsert 138 fuse to the molten metal.

Once the molten metal has sufficiently solidified and/or cooled,controller 32 generates control signals directing actuator 52 (shown inFIG. 1) to open mold 122. After the mold has opened controller 32generates a control signal directing actuator 52 to advance ejectionsystem 131 (not shown) along with ejector pin 163 to eject the completedpart from cavity 136 of system 120.

Although the present disclosure has been described with reference toexample embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the claimed subject matter. For example, although differentexample embodiments may have been described as including one or morefeatures providing one or more benefits, it is contemplated that thedescribed features may be interchanged with one another or alternativelybe combined with one another in the described example embodiments or inother alternative embodiments. Because the technology of the presentdisclosure is relatively complex, not all changes in the technology areforeseeable. The present disclosure described with reference to theexample embodiments and set forth in the following claims is manifestlyintended to be as broad as possible. For example, unless specificallyotherwise noted, the claims reciting a single particular element alsoencompass a plurality of such particular elements.

1. A method comprising: positioning an insert within a cavity of a mold;heating the insert wall within the cavity of the mold; and casting amolten metal into the cavity adjacent the insert, wherein a surface ofthe insert absorbs heat from the molten metal to melt and fuse to themolten metal.
 2. The method of claim 1 further comprising providing aninert gas adjacent the surface during heating of the insert.
 3. Themethod of claim 2, wherein the inert gas is provided through a port andwherein the method further comprises moving an ejection pin from a firstposition closing the port to a second position opening the port.
 4. Themethod of claim 1, wherein the surface of the insert and the moltenmetal are from a same family of alloys.
 5. The method of claim 1 furthercomprising applying electrical current to the insert to heat the insertwithin the mold cavity.
 6. The method of claim 5 further comprisingproviding an inert gas adjacent the surface during heating of theinsert.
 7. The method of claim 5 further comprising an electricallyinsulating the insert from the mold.
 8. The method of claim 5 furthercomprising terminating the application of electrical current to theinsert immediately preceding casting of the molten metal into thecavity.
 9. The method of claim 1 further comprising applying a releaselayer to the mold.
 10. The method of claim 9, wherein the release layeris configured to be attracted to the mold due to an electrical chargeapplied to the mold.
 11. An insert molding system comprising: a moldhaving a cavity configured to receive an insert; an insert heatingsystem configured to heat at least a surface of the insert while theinsert is within the cavity to a temperature below a melting temperatureof the surface; and a casting system configured to cast a molten metalinto the cavity adjacent the surface of the insert, the molten metalsupplying heat to the surface of the insert to raise a temperature ofthe surface to above the melting temperature of the surface.
 12. Thesystem of claim 11, wherein the insert heating system comprises aelectrical heating system configured to apply an electrical currentacross the insert.
 13. The system of claim 12 further comprising atleast one electrically insulating member configured to extend betweenthe insert and the mold when the insert is within the mold.
 14. Thesystem of claim 13, wherein the at least one electrically insulatingmember comprises an electrically non-conductive mold component.
 15. Thesystem of claim 13, wherein the at least one electrically insulatingmember includes one or more ceramic materials.
 16. The system of claim12 further comprising a gas introduction system configured to provide aninert gas adjacent to the surface of the insert within the cavity duringheating of the insert.
 17. The system of claim 16, wherein the gasintroduction system provides the inert gas through a shot sleeve of thecasting system.
 18. The system of claim 12 further comprising acontroller configured to generate control signals directing theelectrical heating system to terminate the application electric currentacross the insert prior to the fluid material from the casting systemcontacting the surface of the insert.
 19. The system of claim 11 furthercomprising a gas introduction system configured to provide an inert gasadjacent to the surface of the insert within the cavity during heatingof the insert.
 20. The system of claim 19, wherein the gas introductionsystem introduces the inert gas through a shot sleeve of the castingsystem.